1. Field of the Invention
The present invention relates to a side impact beam for a passenger vehicle, particularly for a vehicle door.
2. Description of the Related Art
Side impact beams composed of hat-shaped profile sections which are open toward the external panelling of a passenger vehicle, particularly the external panelling of a vehicle door, have been found to be preferred door reinforcements because of their high stiffness, their good deformability and high sectional stability in the case of concentric loads.
Because of practical requirements, when a concentric load is applied to side impact beams, approximately the same bending stresses should occur along its entire length. Consequently, in the ideal case, the section modulus would have to linearly decrease from a maximum in a center transverse plane usually located in the middle of the door toward the points where the side impact beam is fastened to the vehicle chassis, particularly at the A-crosstie, B-crosstie and C-crosstie of the vehicle chassis. However, side impact beams constructed in this manner do not have a sufficient stiffness because they resiliently yield too much in the elastic range. On the other hand, side impact beams having a maximum constant section modulus along its entire length have a high stiffness in the elastic range but they buckle prematurely.
In a side impact beam known from PCT/SE 93/00760 with a hat-shaped cross-sectional profile, the resistance is to be ensured by providing the side impact beam with at least one beam portion in which the width of the web decreases in the direction toward a beam end, while the cross-sectional height remains essentially constant. In addition, at least one additional beam portion is provided in which the height decreases in the direction toward the beam end, while the width of the web remains essentially constant. This configuration of the side impact beam is not sufficiently able to meet the criteria expected of such a side impact beam.